Democrats at the party’s national convention Tuesday evening embraced the Black Lives Matter campaign, welcoming to the stage a handful of mothers whose children had died from gun violence or in police custody.

But the party’s focus on black lives drew the ire of a police union that suggested blue lives were being disregarded. And U.S. criminal justice policies under both Democratic and Republican administrations came in for heavy criticism during a protest Tuesday afternoon in the city’s streets.

Seven so-called Mothers of the Movement, whose children were killed by gun violence or in encounters with police, took the convention stage to loud cheers of “black lives matter!”

The women, vocal supporters of Democratic presidential nominee Hillary Clinton, fought back tears as they described how she was their preferred choice to carry on their children’s legacy.

“I am here with Hillary Clinton tonight because she is a leader and a mother who is not afraid to say our children’s names,” said Geneva Reed-Veal, whose daughter, Sandra Bland, died in a Texas jail cell last year.

The group includes the mothers of Trayvon Martin, the unarmed teenager shot while walking to a family friend's home in Florida in 2012, and Eric Garner, who died in 2014 after being put in a chokehold by police in New York.

“Hillary Clinton has the compassion and understanding to support grieving mothers,” said Sybrina Fulton, Martin’s mother. “She has the courage to lead the fight for commonsense gun legislation. She has a plan to heal the divide that so often exists between law enforcement and the community they serve.”

Democratic Presidential candidate Hillary Clinton appears on a large monitor to thank delegates during the second day of the Democratic National Convention in Philadelphia, July 26, 2016.

Spotlight on movement

The women’s appearance marked one of the highest-profile moments yet for Black Lives Matter, and provided a strong contrast with Republican Party presidential nominee Donald Trump, who has repeatedly criticized the racial justice movement.

Trump has slammed Black Lives Matter protesters for “dividing America,” and many in his party say the group is partly to blame for the recent outbreak of shootings of police officers.

Blue Lives Matter

The killings of police have spurred a parallel movement, Blue Lives Matter, which focuses on the well-being of law enforcement officers. Some in this movement say they are offended that Democrats are highlighting the Black Lives Matter activists.

In a statement, the Philadelphia Fraternal Order of Police said it was “shocked and saddened” by the choice of speakers at the Democratic convention, saying organizers should have also included victims of violence against police.

“The Fraternal Order of Police is insulted and will not soon forget that the Democratic Party and Hillary Clinton are excluding the widows and other family members of police officers killed in the line of duty who were victims of explicit, and not implied, racism, and being ‘on duty in blue,’” the statement said.

“Mrs. Clinton, you should be ashamed of yourself, if that is possible,” it continued.

However, some convention speakers did highlight the plight of police officers.

In a speech Tuesday, former Attorney General Eric Holder said he was “profoundly aware that an attack on a police officer anywhere is an attack on our entire society.”

Former Attorney General Eric Holder speaks during the second day of the Democratic National Convention in Philadelphia , July 26, 2016.

But he also stressed that the goal of keeping officers safe “is not inconsistent with ensuring that those in law enforcement treat the people they are sworn to protect with dignity, respect, and fairness.”

“We must commit ourselves to both goals,” said Holder, who as attorney general carried out federal investigations into several police departments accused of racial discrimination.

Protesters reject Clinton, DNC

During the afternoon, a so-called Black Resistance March exposed animosity toward both political parties. A diverse group of protesters carried signs reading “Hillary, Delete Yourself” and “Hillary Has Blood On Her Hands” as they chanted slogans calling for the overthrow of the “whole damn system.”

Jamar James of Sicklerville, New Jersey, was carrying a red, white and blue coffin marked with the letters “DNC” as he marched with several hundred other protesters.

“This is a coffin for the DNC, for the end of the Democratic Party,” he said. “Democrats pay us lip service most of the time, but I don’t trust them. You can’t trust the Democratic Party to do anything that isn’t in the corporations’ best interest.”

As they marched through the city, protesters carried signs displaying the names of African-Americans killed by police. At times, they erupted in chants, calling police “pigs.”

“For people of color in this country, this is a critical moment,” said Ewuare Osayande, a poet, author and activist. “Because we’re witnessing the fact that the very electoral system is not structured to respond to our concerns.”

“Even under the watch of our nation’s first African-American president, we are witnessing the escalation or the visible recognition of police murder, and yet that administration has not been able to stop the bloodshed,” he said.

FILE - Police arrest Black Lives Matter leader DeRay McKesson during a protest along Airline Highway, a major road that passes in front of the Baton Rouge Police Department headquarters on July 9, 2016.

Tensions over Bill Clinton

Some African-American activists have taken issue with Hillary Clinton’s husband, Bill Clinton, whose policies as president – from 1993 into early 2001 – helped lead to rapid prison growth and extended prison sentences.

Others have been critical of Hillary Clinton’s 1996 reference to certain black youths as “super predators,” a term she has since apologized for.

But the overwhelming majority of African-Americans appear willing to support Clinton over Trump. Most polls show 89 to 90 percent of blacks backing her.

While many of the marchers said they would vote for Clinton, others said they support Green Party candidate Jill Stein. Some simply expressed disillusionment.

Richard Kossally from New York City said he sees Trump as a “racist,” but said he is opposed to both major parties.

“Black people will suffer regardless of who wins,” he said. “It doesn’t really matter which one is in office.”